I have been struggling some time before hard to configure Squirrel Mail on my Microsoft outlook 2007. It is very simple.
Here is the configuration settings
The main problem comes in choosing incoming mail server and outgoing mail server. Use the same address which you use for logging into your email account through web browser. Like I used http://mail.laser.com
and be careful to use your login details to enter as you use to login into yoour email and not which you use to login into mail.laser.com